Leaders from 47 countries, including the Philippines, begin arriving tomorrow (Sunday) for a two-day summit to talk about the threat of nuclear terrorism.

President Arroyo is arriving on Monday, officials revealed, in time for the start of the summit at the Washington Convention Center in downtown DC.

The Philippines assumes the presidency of the Review Conference of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) next month in New York.

The treaty, which bounds signatory countries, not to spread or allow other countries to spread nuclear weapons, fissile materials and nuclear weapons technology, is reviewed every five years under the auspices of the United Nations.

Ambassador Libran Cabactulan, a career diplomat who served as Dept. of Foreign Affairs senior special assistant for nuclear disarmament and non-proliferation, takes over the presidency.

Observers described the Philippine’s role as that of the “honest arbiter” in next month’s discussions which are expected to be dominated by concerns over Iran and North Korea.

North Korea is the only country that’s ever pulled out of the NPT.

India and Pakistan, which is known to have nuclear weapons, and Israel, which is widely believed to have nuclear weapons but have has never acknowledged it, have not signed the NPT.

Iran signed the NPT but is suspected to be trying to build nuclear weapons.

Despite the Philippine’s seemingly primal role in nuclear non-proliferation, no meetings are scheduled between Presidents Obama and Arroyo – at least according to the latest White House briefing last Friday.

On Sunday, President Obama will hold separate bilateral meetings with the leaders of India, Kazakhstan, South Africa and Pakistan, and a courtesy call by President Umaru Yar’Adua of Nigeria.

On Monday, the US Chief Executive will hold another round of sidebar meetings with King Abdullah of Jordan, Malaysian Prime Minister Mohamed Najib Abdul Razak, President Serzh Sargsian of Armenia, and President Hu Jintao of China.

Militant Fil-Ams are holding protests near the White House on the eve of President Arroyo’s arrival.

The group “Never Again to Martial Law Coalition” assailed the Philippine president’s participation in the nuclear summit as “political hypocrisy” because of her dismal human rights record.

“President Arroyo basks in power with greed and corruption,” their statement read.

They cited the arrest of 43 medical workers in Morong, Rizal; the alleged cover-up of the Maguindanao massacre culprits; and the alleged abduction and torture of Fil-Am Melissa Roxas.

“Many Filipinos fear that she will not relinquish power by manipulating a failure of elections on May 10, which can be an excuse to declare Martial Law and form a junta with her at the head,” the group declared.

The DC police gave them a permit to hold the rally across the White House south lawn.

Large swaths of downtown DC will be locked down starting Sunday, under a security clamp-down that’s being compared with President Obama’s historic inauguration last year.

Philippine officials are keeping a tight lid on the President’s schedule in DC.

On Tuesday, President Obama will chair day-long plenary sessions which will focus on “national actions to secure nuclear material” and “international measures to strengthen the international system for dealing with nuclear security” according to Deputy National Security Adviser Ben Rhodes.

President Obama is investing in nuclear security because that is America’s biggest fear – a nuclear bomb in the hands of rogue states or worse, terrorists.

“We know that terrorist groups, including al-Qaeda, are pursuing materials to build a nuclear weapon, and we know that they have the intent to use one…this would be a catastrophic danger to American and global security were they able to carry out that kind of attack,” Rhodes said.

The Cold War and the threat of nuclear annihilation, Secretary Clinton said, “seems so long ago, but it was so real. It would be easy to think that’s a relic of the past. But that is not the case.”

She explained a 10-kiloton nuclear explosive detonated in Times Square in New York City would instantly kill a million people (the bomb dropped on Hiroshima was 18-kiloton and killed 140,000 people).

Many more would suffer from the fall-out and radiation. “Beyond the human cost, a nuclear attack would touch off a tsunami of social and economic consequences,” Secretary Clinton warned.

And as the lessons of 9/11 show, the ripples of such an attack would travel all across the world several times over.