US Secretary of State Hillary Clinton spent Monday engaged in "intensive diplomacy" concerning North Korea's reported nuclear test, according to the State Department. She had spoken by phone to her Japanese and South Korean counterparts by press time and was due to consult with Chinese and Russian leaders later in the day. While it wasn't immediately clear what steps the US would be taking in response to the test, US President Barack Obama paused before his Memorial Day visit to Arlington Cemetery Monday morning to denounce the "blatant violation of international law." He called the test a threat to the populations in the region and a violation of North Korea's own commitments made under multilateral negotiations - known as the six-party talks - over ending its nuclear program. "The United States and the international community must take action in response," he declared. "North Korea will not find security and respect through threats and illegal weapons." Obama added, "We will work with our friends and our allies to stand up to this behavior and we will redouble our efforts toward a more robust international nonproliferation regime that all countries have responsibilities to meet." While the US was calling for international cooperation, analysts in Washington said that the nuclear test - and the American response to it - had global implications. "Given the cooperation between North Korea and Iran, there is reason to fear that North Korea and Iran may be sharing data on nuclear matters, as they do on ballistic missiles," John Bolton, the former undersecretary of state for arms control and international security, said on Fox News Monday. "This is a threat not just in northeast Asia, but potentially in the Middle East as well." And Ilan Berman, vice president for policy of the American Foreign Policy Council, said that Teheran will be watching the American response closely, to apply it to its own circumstances. "Everyone's taking their cues from this," he said. "The Iranians, based on how America responds or doesn't respond, are going to make assumptions about how far they can go in their nuclear program, how far they can go in their missile program without eliciting a serious response from America." He pointed to a missile test that North Korea held earlier this spring despite opposition from the White House as paving the way for this week's nuclear test announcement. Despite America's verbal condemnation ahead of the missile test, Berman said, "the response was pretty dramatic in its nonexistence; it was a pretty telling moment." "The expectation is that the Obama administration's not going to have a very steely approach to this," he added. If that turns out to be the case, he said, "The Iranians could be justified in concluding that Washington is going to respond the same way to them." Bolton described the test as "a real moment of truth for the Obama administration." The US ambassador to the UN under former president George W. Bush recommended that the US add North Korea back to its state-sponsors of terrorism list, as well as impose tough UN sanctions. Berman suggested that tying up its financial transactions - an effective strategy the Bush administration used before relaxing its approach to North Korea - as well as sanctions could be employed. "If you choose to do nothing, you still have made a choice, and everyone understands that you have made a choice," Berman said.