Written byRamya Patelkhana
The officials say Syrian President Bashar al-Assad's government has kept some chemical weapons stock despite the US-Russian deal under which it had to hand them over for destruction.
The recent attacks in Syria suggest the government is producing weapons, they said.
The US officials suspect the Syrian Government was responsible for the latest chlorine gas attacks in Damascus on rebel-held areas, including one on 1 February which killed three civilians in Eastern Ghouta.
The officials said chemical attacks could also be carried out as an "instrument of terror," adding, "They think they can get away with it if they keep it under a certain level."
Following the chlorine gas attack in Eastern Ghouta, US State Department spokesman Heather Nauert tweeted: "Russia is making the wrong choice by not exercising its unique influence. To allow Syria regime to use chemical weapons against its own people is unconscionable. We will pursue accountability."
The US officials said instead of handing over chemical weapons, Syria "evolved" and used them occasionally since the "deadly sarin attack" on a rebel-held area in April.
This prompted the US to carry out a missile-strike on a Syrian air-base, from which the attack was believed to be launched.
Officials said Syria is also making it harder to trace the origin of the weapons.
Apart from chemical weapons, Syria is reportedly making new types of weapons for improving its military capabilities or for escaping "international accountability", suggested the Trump administration officials.
They added ISIS also carries out attacks using sulfur mustard and chlorine. The chemicals are delivered using shells or improvised explosive devices.
These attacks are similar to the ones allegedly being carried out by the government.
The US officials blamed Russia -Assad's key ally- for supporting the Syrian Government, echoing US Secretary of State Tillerson's accusation that Russia bears responsibility for failing to enforce the chemical-weapon ban. Meanwhile, Russia denied any involvement. Syria stated it didn't carry out the attacks either.
One senior US official stated, "We reserve the right to use military force to prevent or deter the use of chemical weapons."
Another said the Trump administration hopes that diplomatic pressure and international sanctions would stop Syrian President Assad's chemical weapons program.
They didn't comment on whether US military was going to respond to the latest attacks with fresh missile strikes.
A US official said that if the international community doesn't act quickly to stop Assad's weapons program, the chemical weapons developed by Syria could spread beyond borders, even to the US. He warned, "It will spread if we don't do something."
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