North Korea fired two short-range missiles into the sea on Thursday, South Korea’s military said, the first weapons launches in more than two months as North Korean and US officials struggle to restart nuclear negotiations. The South’s Joint Chiefs of Staff said the missiles fired from around the North’s eastern coastal town of Wonsan flew about 430 kilometers (270 miles) before landing in the waters off the country’s east coast. A South Korean defense official, requesting anonymity citing department rules, said that the United States analyzed one of the missiles that flew longer than 430 kilometers. The official said that an initial South Korean analysis showed both missiles were fired from mobile launchers and flew at the maximum altitude of 50 kilometers (30 miles). Some observers say the North’s intentions could be to show the US and others what would happen if diplomacy fails. But the relatively short flight distance by the missiles also suggests the launches were not a major provocation, such as a test of a long-range missile capable of reaching the US mainland, and that North Korea doesn’t appear to be pulling out of a US-led diplomacy on its nuclear program. In recent days, North Korea has been ramping up the pressure on the US and South Korea over their expected summertime military drills that it views as an invasion rehearsal. Last week, the North said it may lift its 20-month suspension of nuclear and long-range missile tests in response to the drills. President Donald Trump has considered the weapons moratorium a major achievement in his North Korea policy. Some experts say it was a negotiating tactic by North Korea to take issue with the drills in order to get an upper hand ahead of the possible resumption of talks. North Korea wants to get widespread sanction relief to revive its dilapidated economy, but US officials want the country to take significant disarmament steps before they give up the leverage provided by the sanctions. A senior US official said the Trump administration was aware of the reports of a short-range projectile launched from North Korea. The official, who spoke on condition of anonymity to provide a response, said the administration had no further comment at this time. “If they were ballistic missiles, they violate the UN sanctions, and I find it extremely regrettable.” Japan’s Defense Minister Takeshi Iwaya told reporters in Tokyo. It was the first such launch since Seoul said North Korea fired three short-range missiles off its east coast in early May. Many experts said at the time that those missiles bore a strong resemblance to the Russian-designed Iskander, a short-range, nuclear-capable ballistic missile that has been in the Russian arsenal for more than a decade. South Korea’s military said it and the US military were analyzing details of Thursday’s launches. South Korea said it was monitoring possible additional launches by North Korea. During a third summit at the Korean border late last month, Trump and North Korean leader Kim Jong Un agreed to resume nuclear negotiations, which had been deadlocked since their second summit in Vietnam in February ended without an agreement because of disputes over US-led sanctions. Both the launches in May and on Thursday won’t end that weapons test moratorium, which applies to firing intercontinental ballistic missiles. On Tuesday, North Korean state media said Kim inspected a newly built submarine and ordered officials to further bolster the country’s military capabilities. The Korean Central News Agency said the submarine’s operational deployment “is near at hand.” After analyzing North Korea-dispatched photos of the submarine, experts said the submarine likely has three launch tubes for missiles. South Korean government documents say North Korea has about 70 submarines, but analysts say they mostly have a single launch tube. The construction of such a new submarine suggests North Korea has been increasing its military capability despite nuclear diplomacy that it began with the United States early last year. The latest launches came amid a recent flare-up of tensions on the Korean Peninsula after South Korean fighter jets on Tuesday fired hundreds of warning shots to repel a Russian reconnaissance plane that Seoul says violated its territorial airspace. Before that alleged intrusion, Seoul said Russian and Chinese warplanes including the reconnaissance aircraft made an extremely unusual joint entrance into South Korea’s air defense identification zone, prompting South Korean military jets to scramble. Russia and China have said they carried out their first joint patrol in the waters between the Korean Peninsula and Japan but said none of their planes violated South Korea’s airspace. Experts say the joint patrol may have been aimed at testing readiness of trilateral security cooperation among the United States, South Korea and Japan.