Saudi Arabia may want to buy nuclear weapons from its ally Pakistan to deter Iran but the latter can ill afford to sever relations with the same nation.

The BBC’s Mark Urban reported earlier this month that Pakistani atomic weapons were “sitting ready for delivery” to Saudi Arabia, raising the possibility that the oil kingdom acquired such weapons before its nemesis Iran did.

Pakistan promptly denied the report. Zachary Keck, the associate editor of The Diplomat , writes in The National Interest that it has little reason to make the transaction. He believes Pakistan’s fear of alienating Iran is the biggest deterrent to selling Saudi Arabia nuclear weapons.

Pakistan plans to build a natural gas pipeline into Iran, a project that both Saudi Arabia and the United States oppose. If it were to send nuclear weapons to Saudi Arabia — which would significantly weaken the advantage Iran gains from developing the capacity to build such weapons itself — the Shia country would surely suspend the project as well as existing gas sales to Pakistan. For a country that is having to cope with power outages that sometimes last up to twenty hours per day, sparking riots and crippling industries, that would be unbearable.

Worse, Iran would likely deepen its relations with Pakistan’s rival India. By selling the Saudis nuclear weapons, “Pakistan would have guaranteed it is surrounded by India on three sides,” writes Keck — because India is also expanding its influence in Afghanistan. “For a country as obsessed with strategic depth as Pakistan, this situation would be nothing short of a calamity.”

The Saudis seem increasingly alarmed by the prospect of a nuclear Iran. King Abdullah exhorted his ally the United States to “cut off the head of the snake” by launching military strikes to destroy its nuclear facilities, an American diplomatic cable leaked in 2010 claimed. The king’s former spy chief, Turki bin Faisal Al Saud, warned a year later that the ruling family in Riyadh would “consider all possible options, including the possession of these weapons” to defend itself. But where would it get them? It is highly unlikely that any Western power will supply Saudi Arabia with atomic weapons or even the technology to make them. Pakistan might be its only hope.

The two Sunni countries have maintained an alliance since the 1960s when Saudi Arabia supported Pakistan in its wars against India and opposed the secession of East Pakistan which nevertheless became Bangladesh in 1971. It also collaborated with Pakistan and the United States in supporting the Afghan mujahideen in their resistance to the Soviet occupation in the 1980s when the kingdom financed Pakistan’s military modernization.

Relations have been strained in recent years, however, as Saudi Arabia expanded its trade with Iran. The kingdom is now India’s main oil provider and employs some two million Indian workers. India and Saudi Arabia traded goods and services worth $25 billion between them in 2011 when Pakistani-Saudi trade didn’t exceed $5 billion. The Saudis still provide financial support to the government in Islamabad which they see as a hedge against Iran. But when Pakistan is so dependent on Iranian gas, that doesn’t seem a very compelling basis for an alliance anymore.