US President Barack Obama on Friday pledged with Japan\'s new leader to take a firm line on a defiant North Korea but the two sides also tried to calm rising tensions between Tokyo and China. Prime Minister Shinzo Abe carefully avoided disagreements with Obama after previous Japanese governments\' rifts and declared: \"The alliance between Japan and the United States is back now. It\'s completely back.\" Obama promised to work closely with the conservative leader, whose Liberal Democratic Party swept back into power in December on a platform that includes boosting defense spending and aggressively stimulating a long-flaccid economy. \"You can rest assured that you will have a strong partner in the United States throughout your tenure,\" Obama told Abe in the Oval Office, calling the alliance with Japan \"the central foundation\" for US policy in Asia. Obama said the two leaders discussed \"our concerns about the provocative actions that have been taken by North Korea and our determination to take strong actions in response.\" North Korea carried out its third nuclear test on February 12, ignoring warnings even from its ally China. Abe, who first rose to political prominence as an advocate for a tough line on North Korea, said he agreed with Obama\'s position of not offering \"rewards\" to Pyongyang and on the need for a new UN Security Council resolution. But the White House appeared to want to lower the temperature between Japan and China, which has increasingly sent vessels near Japanese-controlled islands known as the Senkaku in Japanese and Diaoyu in Chinese. Obama did not mention the issue but Secretary of State John Kerry, in a separate meeting with Japan\'s Foreign Minister Fumio Kishida, said he wanted to \"compliment Japan on the restraint it has shown.\" The meetings came hours after Beijing lashed out at Abe over a newspaper interview in which he charged that China would eventually hurt its investment climate through assertive actions in the region. Abe said the US-Japan alliance was \"a stabilizing factor\" and -- in remarks he nudged his translator to read out -- added: \"We have always been dealing with the Senkaku issue in a calm manner and we will continue to do so.\" The Japanese leader later spoke in stronger terms in an address at a think tank. While saying he wanted to cooperate with China\'s incoming leader Xi Jinping, Abe insisted that the islands belonged to Japan. \"We simply cannot tolerate any challenge now and in the future. No nation should make any miscalculation about the firmness of our resolve,\" Abe said at the Center for Strategic and International Studies. The exchange marked a different tone than one month ago, when then secretary of state Hillary Clinton warned China not to challenge Japan\'s control of the islands, triggering a rebuke from Beijing. Obama put a strong emphasis on Asia in his first term but has faced chronic political turbulence in Japan. Abe is the fifth Japanese prime minister since Obama was elected president. Abe, who was also prime minister from 2006 to 2007, is known for his outspoken views on security and on World War II history -- a persistent sore point in relations with South Korea and China. He has been more circumspect in his comments since returning to office. Abe said Friday he sought a \"good relationship\" with South Korea despite friction with the fellow US ally over a separate set of barely inhabited islands. Abe also said that Japan would sign the Hague treaty on parental abductions, a key concern for US lawmakers due to Japanese courts\' refusal to grant custody to foreigners. But the Obama administration held firm on the Trans-Pacific Partnership, a proposed free trade pact that is a cornerstone of US strategy in the region. The Liberal Democratic Party had said during the election that Japan would only enter talks if certain sectors are off the table. But the two governments issued a statement saying that no sector would have a prior exemption. Abe, who said he would decide soon whether to join the talks, expressed assurance that the final negotiated trade pact could include exemptions. Japan\'s powerful farmer lobby opposes the deal, fearing a flood of foreign competition.