On Sunday, U.N. chief Ban Ki-moon also asked the North to refrain from further missile tests.
South Korea suspended its humanitarian aid in response to missile tests by North Korea last July.
The July missile tests were scarcely mentioned during the ASEAN Regional Forum in Brunei earlier this month.
The UN Security Council banned North Korea from missile tests after nuclear tests conducted in 2006 and 2009.
Then came news of Iranian missile tests, and oil quickly shot up again.
Security Council has issued three separate resolutions on North Korea, in response to its nuclear and missile tests since 2006.
For its part, however, the Soviet Union is demanding that such encryption be prohibited on both ballistic and non-ballistic missile tests.
"It seems that markets reacted quite wholly to the images yesterday released of Iran's missile tests, " said Lawrence Poole, analyst with Global Insight.
The talks are expected to focus on the Middle East, the stand-off over Iran's nuclear programme, North Korea's missile tests, energy security and the Balkans.
How big a setback do you think it was for relations in this part of the world that he carried out those missile tests in July?
The US, Japan and South Korea are seeking a response in the UN Security Council, which banned North Korea from missile tests after nuclear tests in 2006 and 2009.
Mr Clinton wanted to impress on Mr Jo that there must be no more missile tests, like the one that sent a far-flying rocket over Japan two years ago.
South Korean Defense Ministry spokesman Kim Min-seok told reporters Tuesday there were no signs that North Korea could conduct additional nuclear and missile tests anytime soon, or launch some other provocation.
The increased threat of further conflict in the Middle East intensified the push, adding to late gains on Thursday made after an extra batch of Iranian missile tests and more tub-thumping rhetoric.
Against the backdrop of Iranian missile tests and threats of retaliation, United States Secretary of State Condoleezza Rice said on Thursday that the United States would help defend Israel if it were attacked.
His officials point to Mr Kim's promise to hold off from further missile tests, and his readiness to live up to North Korea's commitments under the 1994 nuclear deal, as evidence of success.
Still, the United States and South Korea have raised their defense postures, as has Japan, which deployed PAC-3 missile interceptors in key locations around Tokyo on Tuesday as a precaution against possible North Korean ballistic missile tests.
On Tuesday, Yediot Aharonot reported that Israeli analysts who reviewed videotapes of North Korea's missile tests concluded that alongside the various short range Scuds it sent over the Sea of Japan, Pyongyang also launched a Taeopodong-2 multi-stage long range missile capable of reaching Alaska.
It's not over yet -- Mr. Bush is said to be making a decision this week -- but the basic thrust is as follows: The U.S. would agree to delay withdrawing from the Treaty in return for Russia allowing the U.S. to proceed with anti-missile tests the Treaty now bans.
U.S. Deputy Defence Secretary Paul Wolfowitz said in Washington that the Pentagon planned to begin construction next April for missile defence tests that could violate the treaty.
Talks between the two countries have stalled during the past year over the United States' plan to move ahead on tests of its proposed missile defence system which go against Russia's wishes.
But the practical, stability-preserving, tests of Mr Bush's missile-defence plans are yet to come.
The whole purpose of tests - whether of missiles or missile interceptors - is to improve them.
Repeated failures of the Bulava intercontinental ballistic missile caused embarrassment for Russia, though two successful tests were reportedly conducted last year.
Evolutionary sea-based defenses, an early version of which conducted a successful intercept of a short-range ballistic missile two months ago, meet both of these tests.
Pentagon officials promised to press forward with plans for more tests of the system after an interceptor missile hit a dummy warhead over the Pacific Ocean on Saturday.
The U.S. and Russia pursued their missile plans in fairly predictable ways--development, flight tests, deployment.
South Korea's foreign minister told MPs on Thursday that the North had moved a missile to the east coast, which is the location for previous military tests.
If that too fails, the Pentagon is unlikely to be able to recommend to Mr Clinton that an anti-missile system is now feasible, even though more than a dozen further tests are planned.
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